This invention relates to a lapping machine for simultaneously polishing both faces of objects of lapping.
As the degree of integration of IC devices increases, wafers for the IC devices and other objects of lapping need to be smoothly and very accurately polished on both sides. For high-accuracy wafer polishing, lapping apparatuses which simultaneously polish the two faces of each wafer are conventionally used. In one such lapping apparatus, wafers are held between upper and lower lapping plates (each pasted with a pad) so as to be fitted in holes in a carrier, and are polished with a flatness error of 1.00 .mu.m or less.
In the prior art lapping apparatus of this type, however, the polished wafers are manually removed from the apparatus and collected in a cassette. Accordingly, the lapping apparatus for simultaneously polishing the two faces of each object has the following drawbacks.
First, the polished wafers are left adsorbed on the upper and lower lapping plates, so that it is difficult to remove the wafers from the plates by hand after polishing.
Secondly, the wafers laid on the carrier after polishing are substantially equal in thickness to the carrier, and are fitted in the holes in the carrier. It is therefore hard to remove the wafers manually from the holes, requiring much time and labor.
Thirdly, the surfaces of the wafers, after polishing, are activated and untouchable. At the time of removal, therefore, the wafers need to be held by their edges. Thus, the removal of the wafers from the lapping apparatus is very low in working efficiency, requiring much time and labor.
Finally, the wafers are exposed to the air for a relatively long time due to their prolonged removal from the lapping apparatus. Thus, the surfaces of the wafers may suffer oxidation or the adhesion of dust or other foreign substances.